Economics of solar

Solar on it’s own impacts your cash flow in 2 ways:

  1. Positive cash flow from energy consumption offset savings – Self-Consumption
  2. Positive cash flow from feed-in tariffs

The most savings come from the Self-Consuming of energy. This is when you’re using energy at the same time as generating it. This is most important for commercial tenants who often get no feed-in tariff at all. For more on this see our page on Self-Consumption.

Fortunately for people living in WA, our main network operator Western Power makes available the historical energy usage for energy customers on request. This can often be a reading every 30 mins for the whole year. When you get a commercial quote from Behind the Meter Energy we will run simulations of your historical energy usage alongside different sizes and orientations of solar arrays to find the result that maximises your self-consumption and therefore your energy savings. This way you can have peace of mind that your projected Return on Investment is based on real world data relevant to your individual situation.

Below is the energy flow results of such an analysis carried out for an educational facility in Geraldton. While the average curves are both very similar, due to the day to day variability in both customer energy consumption and solar yield the final self-consumption ratio comes to approximately 80%. For this particular case a system size of 33kW of solar panels was found to be the “sweet spot” that gave best return on investment with projected energy savings in excess of $14,000+GST per year.


For Residential installs you are most likely eligible for the Renewable Energy Buyback Scheme (REBS). This guarantees you a feed-in rate of just over 7c/kWh and while it may not sound like much can easily add up to several hundred dollars a year for a standard system size.

The following is an example of how cash flow was affected during summer at a residential install in Geraldton where monitoring was installed:


At the same address on the darker and colder months of the year the savings are still significant:


The savings will be greater the more energy is consumed directly from the solar panels. The savings in the above example were achieved while only using 38% of the energy directly in December and 42% directly in August. This is typical for most households.